Do "True 50/50 Rails" have their Apex on 50% of the foil/thickness of the board?

[stoneburner]

John Mellor’s rail “contour gauge” photo can be found in this post.

Soft vs hard rails on weak and strong waves

I think your observations/opinions are basically sound.  I think you should also consider quantitating the overall thickness of the profile and most importantly, how and where the thickness tapers from end to end (foil.)  You are hitting it with your comments on “pinching” - too much or too far up and you can indeed introduce a tracking tendency.  I’d go so far as to say that rail specs on a custom board are easily one of the hardest details to convey to your shaper.  Personal preferences are ea…